Medizinische Klinik I mit Poliklinik, Universität Erlangen-Nürnberg, Erlangen. Felix.Stickel@med1.imed.uni-erlangen.de
Kava extracts are obtained from the rhizoma of the kava shrub (Piper methysticum) and contain various pyrones which are used as herbal anxiolytic remedies for generalized anxiety syndromes of low and intermediate grades. The commonly recommended daily dose of 60-120 mg kavapyrones and the duration of the therapy of up to 3 months should not be increased without consultation of a physician and were not followed by most patients, since herbal drugs are considered by the population not only as effective but also as safe. Whereas kava extracts are well tolerated by most patients and rare side effects are rapidly reversible upon drug discontinuation, there are suspected hepatotoxic reactions reported during the last years in temporal and not necessarily causal association with a therapy with kava extracts. Almost 80 % of the patients took kavapyrones in overdose (maximally 480 mg/d) and/or for a prolonged time of more than 3 months up to 2 years. Additional risks factors include co-medication with up to 5 other chemically defined or herbal drugs with in part potentially hepatotoxic properties as well as a genetic deficiency of the hepatic microsomal cytochrome P450 2D6. Severe clinical courses with liver transplantation and possible fatal outcome occurred in 7 patients with overdose and/or long duration of the therapy with kavapyrones. Preventive measures should therefore include a dose of 120, maximally 210 mg kavapyrones per day for 1 month, maximally 2 months, as well as a prescription by a physician. Laboratory test (ALT and gamma-GT) should be done before and during the therapy, and co-medication and alcohol consumption should be avoided. With these measures the hepatotoxic risks under the treatment with kavapyrones might be minimized which are also available via internet and from abroad with possible severe consequences when taken without medical supervision.
Mesh-terms: Anti-Anxiety Agents :: poisoning; Drug Interactions; English Abstract; Hepatitis, Toxic :: diagnosis; Hepatitis, Toxic :: etiology; Hepatitis, Toxic :: mortality; Humans; Kava :: poisoning; Liver Function Tests; Overdose :: diagnosis; Overdose :: etiology; Overdose :: mortality; Phytotherapy :: adverse effects; Plant Extracts :: poisoning; Pyrones :: poisoning; Survival Analysis;
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Department of Gastroenterology, Asklepios Klinik Harburg, Hamburg, Germany. st.christl@asklepios.com
Liver toxicity from the use of kava dietary supplements has been reported, but little is known about the side effects of traditional kava preparations. We present a case study of a tourist who developed serious toxic liver disease after consumption of kava beverages in traditional Samoan kava ceremonies.
Amy C Brown,
Janet Onopa,
Peter Holck,
Pakieli Kaufusi,
Derek Kabasawa,
Winston J Craig,
Klaus Dragull,
Arieh M Levine,
Jonathan D Baker
Department of Complementary & Alternative Medicine, John A. Burns School of Medicine, University of Hawaii at Manoa. Honolulu, Hawaii. USA.
Purpose. To determine the effects of traditionally prepared kava beverages on the liver function tests of regular kava beverage consumers in a population of Tongan and non-Tongan residents of Hawaii (Oahu). Methods. The liver function tests of 31 healthy adult kava drinkers were compared against a control group of 31 healthy adult non-kava drinkers. Subjects were recruited from the general population, a kava bar, and Tongan kava drinking circles. The liver function profile included AST, ALT, ALP, GGT, and bilirubin (total and direct). Other tests included total protein, albumin, and screens for viral hepatitis and hemochromatosis when indicated. Results. Chronic kava beverage consumption was associated with elevation of GGT in 65% of the kava drinkers versus 26% in the controls (P =.005). ALP was elevated in 23% of kava drinkers versus 3% in the controls (P =.053). Conclusion. Heavy kava beverage consumption was associated with significantly elevated GGT levels.
Office of Scientific Review, National Center for Complementary and Alternative Medicine, National Institutes of Health, Suite 401, 6707 Democracy Boulevard, Bethesda, Maryland 20817, USA.
With words such as AIDS, allergy and autoimmunity embedded in the popular lexicon, we often equate health with the precision and the tenor of responses to allergens and microorganisms. This leads many people to seek their own solutions to sustain, restore or even boost their immune competence, hoping to live more comfortably and longer. Here, we consider the social and clinical contexts in which these promises of enhanced immunity are pursued through popular practices known as complementary and alternative medicine and the evidence that supports these.
Clinical Pharmacology Research Core, Medical Oncology Clinical Research Unit, National Cancer Institute, 9000 Rockville Pike, Bldg 10, Room 5A01, Bethesda, Maryland 20892; e-mail: sparreba@mail.nih.gov
PURPOSE Interest in the use of herbal products has grown dramatically in the Western world. Recent estimates suggest an overall prevalence for herbal preparation use of 13% to 63% among cancer patients. With the narrow therapeutic range associated with most anticancer drugs, there is an increasing need for understanding possible adverse drug interactions in medical oncology. METHODS In this article, a literature overview is provided of known or suspected interactions of the 15 best-selling herbs in the United States with conventional allopathic therapies for cancer. Results Herbs with the potential to significantly modulate the activity of drug-metabolizing enzymes (notably cytochrome P450 isozymes) and/or the drug transporter P-glycoprotein include garlic (Allium sativum), ginkgo (Ginkgo biloba), echinacea (Echinacea purpurea), ginseng (Panax ginseng), St John' s wort (Hypericum perforatum), and kava (Piper methysticum). All of these products participate in potential pharmacokinetic interactions with anticancer drugs. CONCLUSION It is suggested that health care professionals and consumers should be aware of the potential for adverse interactions with these herbs, question their patients on their use of them, especially among patients whose disease is not responding to treatments as expected, and urge patients to avoid herbs that could confound their cancer care.
Block Center for Integrative Cancer Care, Evanston, Illinois, and the Program for Collaborative Research in the Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago.
Insomnia and other sleep disturbances are common in cancer patients. Insomnia is a multifactorial health concern that currently affects at least 1 in 3 cancer patients, and yet most insomnia sufferers do not consult their physician regarding pharmaceutical options for relief. Use of hypnotic drugs (primarily benzodiazepines) is associated with increasing tolerance, dependence, and adverse effects on the central nervous system. While hypnotic drug use declined substantially in the past decade, the use of herbal sedatives appeared to increase. Mostly self-prescribed by lay people, herbal sedatives hold widespread appeal, presumably because of their lower cost and higher margin of safety when compared to pharmaceuticals. Studies of better-known herbal sedatives, notably valerian and kava, showed moderate evidence for both safety and efficacy for valerian while revealing disturbing toxicity concerns for kava. Milder sedatives or anxiolytics in need of clinical study include German chamomile, lavender, hops, lemon balm, and passionflower; St. John's wort may have anxiolytic effects with relevance to sleep. Herb-drug interactions are a possibility for some of these species, including St. John's wort. Although sufficient evidence exists to recommend some of these agents for short-term relief of mild insomnia, long-term trials and observational studies are needed to establish the safety of prolonged use as well as overall efficacy in the context of cancer treatment and management.
Faculty of Pharmacy, University of Sydney, Sydney, NSW, Australia.
In recent years, kava kava ( Piper methysticum, Forst. f., Piperaceae) has been implicated in a number of liver failure cases. Ever since this has kept the scientific world busy. Even though, on closer inspection, the majority of the case reports are probably not connected to kava intake, hepatotoxic effects of kava cannot generally be ruled out. In this article the major theories as to the mechanism of kava hepatotoxicity are summarized. But in spite of all these hypotheses, there is still no satisfactory answer. In any case, further studies, that might hopefully restore the reputation of kava, are required.
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Department of Internal Medicine II, Division of Gastroenterology and Hepatology, Klinikum Hanau, Teaching Hospital of the Johann Wolfgang Goethe-University, Frankfurt/Main, Germany.
BACKGROUND: Kava hepatotoxicity in 20 patients from Germany has been debated worldwide following a regulatory ad hoc causality assessment and ban of kava, an anxiolytic herbal remedy obtained from the rhizome of Piper methysticum Forster. AIMS: We assessed causality with a quantitative structured causality analysis in all 20 cases of patients with liver disease, presented by the German regulatory agency that assumed a causal relationship with the use of kava extracts. METHODS: The quantitative scale of CIOMS (Council for International Organizations of Medical Sciences) in its updated form was employed for causality assessment and quality evaluation of the regulatory data presentation. RESULTS: The regulatory information is scattered and selective, and items essential for causality assessment, such as exclusion of kava independent causes, were not, or only marginally, considered by the regulator. Quantitative causality assessment for kava was possible (n=2), unlikely (n=12), or excluded (n=6), showing no concordance with the regulatory ad hoc causality evaluation. CONCLUSION: The regulatory data regarding kava hepatotoxicity is selective and of low quality, not supportive of the regulatory proposed causality; but instead, is an explanation of the overall causality discussions of kava hepatotoxicity. We are proposing that the regulatory agency reports data in full length and reevaluates causality.
Toxic liver diseases caused by drugs, herbs and dietary supplements are often recognized late because their hepatotoxic potency is considered to be minimal or non-existent and specific laboratory parameters to definitively establish the diagnosis are lacking. As gold standard for the diagnosis, a positive (unintentional) re-exposure test is considered which is seldom available. A system for evaluation is therefore necessary which takes into account various parameters and defines the grades of causality. By means of a qualitative pre-test with a few questions a screening may be possible as to whether the causality is not probable or not evaluable. Subsequently, a quantitative assessment of the degree of the causality with a main test should be done; this corresponds to the slightly modified and well validated score of the CIOMS (Council for International Organizations of Medical Sciences). The evaluation is achieved using various criteria such as latency period, time between the end of the therapy and begin of the reaction, course of values for the enzyme activities of the liver after cessation of the therapy, risk factors such as age, alcohol consumption and comedication, exclusion of diseases of other organs including chronic liver disease, previous information about hepatotoxicity of the alleged substance and possible results of an unwanted re-exposure. The various answers to these questions are quantitatively assessed, the resulting scores added, and finally an assignment to one of the grades of causality is made. If, on the basis of the main test, there are still doubts about the correct diagnosis, a further test is required to consider the differential diagnosis of additional diseases and chronic liver diseases of other causes. This stepwise approach is essential since ad-hoc decisions regarding causality are not without problems, and other diseases as causes for increased liver values are easily overlooked and not treated adequately in time. By means of this procedure an improvement in the drug safety can be expected, which is fruitful for the patient and helpful to the physician in charge, the health institutions and the drug companies.
Medical Department II, City Hospital Hanau, Teaching Hospital of the Johann Wolfgang Goethe University, Frankfurt/Main, Germany.
Kava is a perennial shrub native to some islands of the South Pacific and has been cultivated for centuries to prepare a psychoactive beverage from its rhizoma by means of extraction. Subsequently, kava extracts are commonly used as herbal anxiolytic drugs also in many other countries all over the world including European ones and the USA. Toxicological and clinical studies have shown that kava extracts are virtually devoid of toxic effects with the exception of rare hepatotoxic side effects reported in few patients. When assessed primarily by the British regulatory authority MCA but also by us, a critical analysis of the suspected cases (n = 19) in Germany reveals that only in 1 single patient a very probable causal relationship could be established between kava treatment and the development of toxic liver disease due to a positive result of an unscheduled reexposure test, whereas in another patient there might be a possible association. Out of the remaining 17 cases 12 patients were not yet assessable due to insufficient data and in 5 other cases a causal relationship was unlikely or could be excluded. The German regulatory authority might therefore well be advised to provide now additional information for those 12 patients with so far unsatisfactory data, facilitating a more appropriate assessment of causality. Nevertheless, in the meantime physicians and patients should continue to keep an eye on possible hepatotoxic side effects in the course of kava treatment, to stop the treatment alredy at first suspicion and to start with a careful diagnostic work up ruling out all other causes.
Medizinische Klinik II, Klinikum Stadt Hanau, Akademisches Lehrkrankenhaus der Johann Wolfgang Goethe-Universität, Frankfurt/Main.
Medizinische Klinik II, Klinikum Stadt Hanau, Akademisches Lehrkrankenhaus der Johann Wolfgang Goethe-Universität Frankfurt/Main, Germany.
About 1000 drugs produced world-wide may lead to clinically relevant hepatotoxic reactions which are unpredictable at normal doses and occur at various frequencies. Among these are well established therapeutic drugs which have been in use for years or decades as well as newly introduced drugs, the number of which is steadily increasing. For the development of drug-induced liver disease, various pathogenetic mechanisms, many risk factors and variable latency periods are known. The histological picture may imitate practically all known non-toxic liver diseases from which toxic liver disease needs to be differentiated. Patients under drug therapy require regular medical follow-up with regard to the development of toxic liver disease since the prognosis is only good with early recognition and immediate withdrawal of the alleged drug. Specific therapeutic modalities to prevent toxic liver disease are limited to paracetamol overdosage which is treated by the application of N-acetylcysteine. For other drug-induced liver diseases characterised by a prolonged course, therapy with ursodeoxycholic acid or steroids may be helpful. When fulminant drug-induced liver failure occurs, liver transplantation is the therapy of choice with a better prognosis than a conventional therapy. Despite this therapeutic option more than 40 different drugs are known to have caused lethal forms of toxic liver disease. Physicians have therefore to be alert to early recognize drug-induced liver disease and to withdraw the drug at first suspicion of the diagnosis.
Medizinische Kliniken I und II, Stadtkrankenhaus Hanau, Universität Frankfurt am Main.
Vague upper abdominal pain, weight loss (10 kg) and recurrent bouts of fever had been present for several months in a 77-year-old woman. Abdominal ultrasonography in the region of the head of the pancreas and duodenum had demonstrated several lymphomas, some of them with "air streaking". This finding suggested penetration from the duodenum to neighbouring lymph nodes. Plain film of the abdomen did not show free air, but at gastroscopy a covered perforation into the surrounding lymph nodes was found. At first lymphoma or Crohn's disease were considered in the differential diagnosis. But the finding of acid-fast bacteria in a biopsy from the pelvic crest suggested intestinal tuberculosis with dissemination. This diagnosis was confirmed by the direct demonstration of Mycobacterium tuberculosis in gastric juice. Under tuberculostatic treatment with daily 0.3 g isoniazid, 0.45 g rifampicin, 0.8 ethambutol and 1.5 g pyrazinamide, as well as 50 mg prednisolone to prevent stricture, the size of the tuberculous ulcer had markedly decreased within 2 weeks. Follow-up gastroscopy after 6 months showed almost complete healing without stricture. However rare, gastrointestinal tuberculosis should not be forgotten in the differential diagnosis because it can imitate a large variety of gastrointestinal diseases.
Medizinische Klinik II, Stadtkrankenhaus Hanau.
In order to achieve a hyperthyroid state, rats were treated for 7 days with thyroxine (150 microgram/100 g BW) or triiodothyronine (10 microgram/100 g BW). This regimen resulted in an enhanced activity of the microsomal ethanol oxidizing system. In addition, a decrease of hepatic alcohol dehydrogenase activity was observed under these experimental conditions, whereas hepatic catalase activity remained unchanged. These findings suggest that if chronic ethanol consumption simulates a functional "hyperthyroid hepatic state", increased rates of ethanol metabolism observed following prolonged alcohol intake might therefore be attributed at least in part to an induced activity of the microsomal ethanol oxidizing system in the liver.
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Rolf Teschke,
Ruediger Bahre,
Alexander Genthner,
Johannes Fuchs,
Wolfgang Schmidt-Taenzer,
Albrecht Wolff
Department of Internal Medicine II, Division of Gastroenterology and Hepatology, Klinikum Hanau, Teaching Hospital of the Johann Wolfgang Goethe-University, Frankfurt/Main, Germany.
OBJECTIVES: Black cohosh (BC) is a herbal drug or herbal dietary supplement used for treatment of menopausal symptoms. Recently, however, reports have appeared about the occurrence of rare toxic liver disease in an assumed relationship with the use of BC. METHODS: We have analyzed and reviewed the data of all 69 reported cases with suspected BC hepatotoxicity. Causality for BC was assessed utilizing the scale of the original structured quantitative Council for International Organizations of Medical Sciences (CIOMS), or the main-test as its updated form. RESULTS: With the hepatotoxicity specific causality assessment methods, there was an excluded, unlikely, unrelated or unassessable causality for BC in 68 of 69 cases with liver disease. One patient had a possible causality for BC and a symptomatic cholelithiasis with confounding variables of fatty liver of unknown etiology; unknown BC brand including possible herbal mixture; unknown daily BC dosage; and an unassessable duration of BC usage. In general, the cases of the 69 patients were poorly documented. Confounding variables were: failure to identify the BC product; use of herbal mixtures with multiple ingredients in addition to BC; co-medication with synthetic drugs and dietary supplements including herbal ones; missing temporal association between BC use and development of liver disease; not specified modalities of BC treatment; failure of dechallenge after BC discontinuation; pre-existing liver diseases; insufficiently excluded other liver diseases; presence of alternative liver diseases. CONCLUSIONS: The analysis of 69 cases shows little, if any, supportive evidence for a significant hepatotoxic risk of BC.
Department of Internal Medicine II, Division of Gastroenterology and Hepatology, Klinikum Hanau, Teaching Hospital of the Johann Wolfgang Goethe-University of Frankfurt/Main, Leimenstrasse 20, D-63450 Hanau, Germany. rolf-teschke@klinikum-hanau.de
ETHNOPHARMACOLOGICAL RELEVANCE: Ethanolic and acetonic kava extracts have previously been causally related to rare hepatotoxicity observed in patients from Germany and Switzerland, but causality assessment was not performed in cases of patients having taken the traditional aqueous kava extracts of South Pacific islands or kava-herbs mixtures. AIM OF THE STUDY: To study the possible hepatotoxicity of aqueous kava extracts of the South Pacific Islands. MATERIALS AND METHODS: Causality of hepatotoxicity by aqueous kava extracts and kava-herbs mixtures was assessed, using the updated score of the quantitative CIOMS (Council for the International Organizations of Medical Sciences). RESULTS: Causality was established in five patients from New Caledonia, Australia, the United States and Germany for aqueous kava extracts and kava-herbs mixtures. A comparison with 9 patients from Germany and Switzerland with established causality of hepatotoxicity by ethanolic and acetonic kava extracts reveals that the clinical picture in all 14 patients is similar, independently whether aqueous, ethanolic and acetonic kava extracts or kava-herbs mixtures were used. CONCLUSIONS: Kava hepatotoxicity occurs also with traditional aqueous kava extracts of the South Pacific islands and thereby independently from ethanol or acetone as chemical solvents, suggesting that the toxicity is linked to the kava plant itself with a possibly low quality of the used kava cultivar or kava plant part rather than to chemical solvents.
Department of Internal Medicine II, Division of Gastroenterology and Hepatology, Klinikum Hanau, Teaching Hospital of the Johann Wolfgang Goethe-University, Frankfurt/Main, Germany.
BACKGROUND: Kava hepatotoxicity in 20 patients from Germany has been debated worldwide following a regulatory ad hoc causality assessment and ban of kava, an anxiolytic herbal remedy obtained from the rhizome of Piper methysticum Forster. AIMS: We assessed causality with a quantitative structured causality analysis in all 20 cases of patients with liver disease, presented by the German regulatory agency that assumed a causal relationship with the use of kava extracts. METHODS: The quantitative scale of CIOMS (Council for International Organizations of Medical Sciences) in its updated form was employed for causality assessment and quality evaluation of the regulatory data presentation. RESULTS: The regulatory information is scattered and selective, and items essential for causality assessment, such as exclusion of kava independent causes, were not, or only marginally, considered by the regulator. Quantitative causality assessment for kava was possible (n=2), unlikely (n=12), or excluded (n=6), showing no concordance with the regulatory ad hoc causality evaluation. CONCLUSION: The regulatory data regarding kava hepatotoxicity is selective and of low quality, not supportive of the regulatory proposed causality; but instead, is an explanation of the overall causality discussions of kava hepatotoxicity. We are proposing that the regulatory agency reports data in full length and reevaluates causality.
School of Medicine, The University of Queensland, Brisbane, Australia, j.sarris@uq.edu.au.
RATIONALE: Piper methysticum (Kava) has been withdrawn in European, British, and Canadian markets due to concerns over hepatotoxic reactions. The WHO recently recommended research into "aqueous" extracts of Kava. OBJECTIVE: The objective of this study was to conduct the first documented human clinical trial assessing the anxiolytic and antidepressant efficacy of an aqueous extract of Kava. DESIGN AND PARTICIPANTS: The Kava Anxiety Depression Spectrum Study was a 3-week placebo-controlled, double-blind crossover trial that recruited 60 adult participants with 1 month or more of elevated generalized anxiety. Five Kava tablets per day were prescribed containing 250 mg of kavalactones/day. RESULTS: The aqueous extract of Kava reduced participants' Hamilton Anxiety Scale score in the first controlled phase by -9.9 (CI = 7.1, 12.7) vs.-0.8 (CI =-2.7, 4.3) for placebo and in the second controlled phase by -10.3 (CI = 5.8, 14.7) vs.+3.3 (CI =-6.8, 0.2). The pooled effect of Kava vs. placebo across phases was highly significant (p < 0.0001), with a substantial effect size (d = 2.24,[Formula: see text]). Pooled analyses also revealed highly significant relative reductions in Beck Anxiety Inventory and Montgomery-Asberg Depression Rating Scale scores. The aqueous extract was found to be safe, with no serious adverse effects and no clinical hepatotoxicity. CONCLUSIONS: The aqueous Kava preparation produced significant anxiolytic and antidepressant activity and raised no safety concerns at the dose and duration studied. Kava appears equally effective in cases where anxiety is accompanied by depression. This should encourage further study and consideration of globally reintroducing aqueous rootstock extracts of Kava for the management of anxiety.
School of Medicine, University of Queensland, Australia. j.sarris@uq.edu.au
OBJECTIVES: To report on the design, significance and potential impacts of the first documented human clinical trial assessing the anxiolytic and thymoleptic efficacy of an aqueous mono-extract of Piper methysticum (kava). The significance of the qualitative element of our clinical trial is also explored. The Kava Anxiety Depression Spectrum Study (KADSS) is a 3-week placebo-controlled, double-blind, cross-over trial involving 60 adult participants (18-65) with elevated stable anxiety and varying levels of depressive symptoms. AIMS: The aims of KADSS are:(1) to determine whether an aqueous standardised extract of kava is effective for the treatment of anxiety;(2) to assess the effects of kava on differing levels of depression; and (3) to explore participants' experience of taking kava via qualitative research. The study also provides preliminary assessment of the safety of an aqueous extract of kava in humans. CONCLUSION: If results reveal that the aqueous kava preparation exerts significant anxiolytic effects and appears safe, potentially beneficial impacts may occur. Data supporting a safe and effective kava extract may encourage a re-introduction of kava to Europe, UK and Canada. This may provide a major socioeconomic benefit to Pacific Island nations, and to sufferers of anxiety disorders.
Use of herbal supplements in the United States continues to grow, and it is estimated that approximately 1 in 3 Americans use unconventional therapies to relieve pain. Eight herbal supplements have been identified that could pose the greatest potential risks in surgical patients. Among these is kava, which is used for a wide spectrum of therapeutic properties, including sedative, anxiolytic, analgesic, and neuroprotective effects. The purpose of this investigation was to examine how kava may modulate pain pathways and how it may interact with morphine using the hot-plate analgesia technique.
Department of Medicine (SG-R), Division of Rheumatology (PA), and Department of Pathology (QH, RM), Nassau County Medical Center, East Meadow, NY; and State University of New York Health Sciences Center, Stony Brook, NY.
Kava-kava is an herbal medication, most commonly used to treat anxiety. It is derived from the roots of the pepper plant, Piper methysticum. A 47-year-old white woman presented with a rash and proximal muscle weakness 2 weeks after ingestion of kava-kava. Her creatine kinase level was elevated at 8654 U/L, and an electromyogram showed a myopathic pattern. Skin biopsy and muscle biopsy samples showed changes consistent with dermatomyositis. The patient improved with prednisone and discontinuation of the kava-kava. No similar association between kava-kava ingestion and dermatomyositis has been reported previously.
Kava extracts are used widely for different purposes and were thought to be safe. Recently, several cases of hepatotoxicity have been published. To explore possible mechanisms of kava hepatotoxicity, we prepared and analyzed three different kava extracts (a methanolic and an acetonic root and a methanolic leaf extract), and investigated their toxicity on HepG2 cells and isolated rat liver mitochondria. All three extracts showed cytotoxicity starting at a concentration of 50mug/ml (lactate dehydrogenase leakage) or 1mug/ml (MTT test). The mitochondrial membrane potential was decreased (root extracts starting at 50mug/ml) and the respiratory chain inhibited and uncoupled (root extracts) or only uncoupled (leaf extract) at 150mug/ml, and mitochondrial beta-oxidation was inhibited by all extracts starting at 100mug/ml. The ratio oxidized to reduced glutathione was increased in HepG2 cells, whereas the cellular ATP content was maintained. Induction of apoptosis was demonstrated by all extracts at a concentration of 150mug/ml. These results indicate that the kava extracts are toxic to mitochondria, leading to inhibition of the respiratory chain, increased ROS production, a decrease in the mitochondrial membrane potential and eventually to apoptosis of exposed cells. In predisposed patients, mitochondrial toxicity of kava extract may explain hepatic adverse reactions of this drug.
